From: Peter Maydell <peter.maydell@linaro.org>

When we converted the LDAPR/STLR instructions to decodetree we
accidentally introduced a regression where the offset is negative.
The 9-bit immediate field is signed, and the old hand decoder
correctly used sextract32() to get it out of the insn word,
but the ldapr_stlr_i pattern in the decode file used "imm:9"
instead of "imm:s9", so it treated the field as unsigned.

Fix the pattern to treat the field as a signed immediate.

Cc: qemu-stable@nongnu.org
Fixes: 2521b6073b7 ("target/arm: Convert LDAPR/STLR (imm) to decodetree")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2419
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20240709134504.3500007-2-peter.maydell@linaro.org
(cherry picked from commit 5669d26ec614b3f4c56cf1489b9095ed327938b1)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
index 8a20dce3c8..6cc29a4bce 100644
--- a/target/arm/tcg/a64.decode
+++ b/target/arm/tcg/a64.decode
@@ -467,7 +467,7 @@ LDAPR           sz:2 111 0 00 1 0 1 11111 1100 00 rn:5 rt:5
 LDRA            11 111 0 00 m:1 . 1 ......... w:1 1 rn:5 rt:5 imm=%ldra_imm
 
 &ldapr_stlr_i   rn rt imm sz sign ext
-@ldapr_stlr_i   .. ...... .. . imm:9 .. rn:5 rt:5 &ldapr_stlr_i
+@ldapr_stlr_i   .. ...... .. . imm:s9 .. rn:5 rt:5 &ldapr_stlr_i
 STLR_i          sz:2 011001 00 0 ......... 00 ..... ..... @ldapr_stlr_i sign=0 ext=0
 LDAPR_i         sz:2 011001 01 0 ......... 00 ..... ..... @ldapr_stlr_i sign=0 ext=0
 LDAPR_i         00 011001 10 0 ......... 00 ..... ..... @ldapr_stlr_i sign=1 ext=0 sz=0
-- 
2.39.2